Conventionally, a Japanese Utility Patent Application Laid-open No. H6-2306 has disclosed an adaptor unit comprising an optical plug which connects each front facet of two ferrules facing with each other and is installed at either male or female opening part in its FIGS. 1 and 2. FIG. 9 of the present application illustrates its structure. The adaptor (19) comprising components such as a dividing sleeve (22) disclosed in the Japanese Utility Patent Application Laid-open No. H6-2306 has been common and well-known.
Recently, as shown in FIGS. 10A-10C, a dividing sleeve unit (u1) is formed by using an approximately tubular dividing sleeve holder (K1, K2) comprising a dividing sleeve (S), and an assembly of components (referred as an adaptor unit hereinafter) in which the dividing sleeve is held indirectly by the main body of the insulation adaptor through a dividing sleeve holder of the dividing sleeve unit (u1) tends to be installed at an opening part of the optical plug or the optical connector.
In the Japanese Utility Patent Application Laid-open No. H6-2306A, a dividing sleeve unit comprising such a structure is illustrated as an alignment tube or an alignment device, and examples for constructing an elastic contact which is used along with the dividing sleeve are also disclosed.
FIG. 11 is a side and sectional view of an adaptor unit 19′ of a general optical connector (optical plug 10′) which is consisted by using such dividing sleeve unit (alignment device; u1) and has been well-known widely in Japan. The dividing sleeve unit u1 in FIG. 11 is inserted and installed in a large through-hole h of the adaptor unit 19′. A tubular main body 2 comprising a ferrule holder 13 which holds a ferrule 18, or a contact point (: the optical contact unit), has a groove g2 formed in an approximately ring shape on the external surface of the opening part of the front end part 3. The dividing sleeve unit u1 fits a projection part g1 which is formed in an approximately ring shape at the back opening part of the dividing sleeve holder K1 illustrated in FIG. 10C with the groove g2 at a point γ illustrated in FIG. 11. As a result, the dividing sleeve unit u1 is fixed in the large through-hole h of the adaptor unit 19′.
A male screw K1a formed on the external surface of the dividing sleeve holder K1 can screw together with a female screw which is formed at the end point of a jig in an approximately cylindrical bar shape. By pulling the jig while the male screw and the female screw remain screwing with each other, the groove g2 and the projection part g1 fitting together at the point γ can be released, and further the dividing sleeve unit u1 can be pulled out of the optical plug 10′ from the opening part 10a. By employing that process, maintenance, or inspection for dirt or stain, and cleaning with tools such as a commercially available cotton-tipped swab can be carried out toward the front facet of the ferrule 18.
The Japanese Patent Application Laid-open No. 2001-749776 discloses more detailed structure of the elastic contact point which holds the ferrule 18 in the optical axis direction with elasticity. That is, for example, sign 12 represents a hole of the groove formed in the tubular main body 2.